Firebase is a Google-backed application development software that enables developers to develop iOS, Android and Web apps.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
HTTP/3 is the third major version of the Hypertext Transfer Protocol used to exchange information on the World Wide Web.
Mailchimp is a marketing automation platform and email marketing service.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.